Stage for v1.4.0 release

[bdebyl]

Proposed Changes

• Changelog cleanup for v1.4.0 release

Description

Changelog cleanup for v1.4.0 release

Checklist

• [x] Read the CONTRIBUTING document.
• [x] Read the CODE OF CONDUCT document.
• [x] Add tests to cover changes.
• [x] Ensure your code follows the code style of this project.
• [x] Ensure CI and all other PR checks are green OR
  • [x] Code compiles correctly.
  • [x] Created tests which fail without the change (if possible).
  • [x] All new and existing tests passed.
• [x] Add your changes to Unreleased section of CHANGELOG.
• [x] Improve and update the README (if necessary).
• [x] Ensure documentation is up-to-date.